In the U.S. Pat. No. 6,951,403 B2 a device for illuminating a generally flat surface is described, which comprises a battery operated light source contained within a housing to which a transparent light conductive illuminating body is mounted. The device may be placed with the illuminating body over a book or other flat surfaces for illuminated viewing through the transparent illuminating body. The illuminating body is tapered in a wedge-shape to deflect the conducted light onto the underline surface. Unfortunately, the described device is less convenient for reading books, which possess in general a curved reading area. The interaction of the curved reading area with the tapered illuminating body leads to a deformed image of the illuminated page. In addition, the page is not lit optimally uniformly, either decreasing reading comfort or increasing power consumption of the device. Furthermore, the device is a relatively thick wedge shaped light guide where the thickness results in relatively high weight and this reduces ease of use. It also results in a relatively high mechanical stiffness making it very difficult to bend the device over a curved reading area.